Stain-eating coatings

ABSTRACT

A coating composition comprising a hardenable film-former and at least 0.5 weight percent of an oxidizing agent sufficient to decolorize a stain on the film-former is disclosed, wherein the oxidizing agent comprises hydrogen peroxide, hypochlorite, and organo-chlorine bleaches and will at least partially decolorize a plurality of stains when applied to the hardened coating, allowed to stand for one hour at room temperature, and evaluated by visual observation of the stain under average overhead fluorescent illumination. The oxidizing agent is not consumed as a catalyst or initiator to polymerize or otherwise cause a reaction in the floor coating before it is applied and before it has hardened. A composition of the invention may include from about 0.8 to about 5 weight percent oxidizing agent and the film-former forms a hardened film resistant to rinsing with tap water.

FIELD OF THE INVENTION

The invention relates to coatings for hardened surfaces. In particular,the invention relates to a coating or a finish capable of removing oreliminating stains. Compositions of the invention are useful in coatingfloors, counters, walls, or other surfaces that commonly suffer fromstaining. Restaurant, grocery, and hospital floors in particular benefitfrom compositions of the invention. Coatings of the invention areprepared by adding an oxidizing agent to a coating composition either atthe time of blending of the coating or at the point of use of thecoating. In preferred embodiments the coating is applied before a stainoccurs thus rendering staining of the surface under the coatingvirtually impossible.

BACKGROUND OF THE INVENTION

Food and beverage stains are an ongoing problem on floor and counterfinishes, particularly those in restaurants and grocery stores. Foodproducts such as mustard, ketchup, coffee, and cola are commonly foundin supermarkets where floor surfaces such as tile floors are employed.When they are spilled they can cause semi-permanent dark yellow, brown,or red stains to the coating itself or the underlying substrate. Workersin these situations are often unable to immediately clean up a spillthat can result in discoloration of the floor finish. These stains canbe very difficult to remove using traditional cleaning and launderingtechniques, and are especially difficult to remove from floor tiles. Forexample, when mustard is spilled on vinyl composite tiles coated with atypical floor finish, both the finish and tiles may stain. Removal ofsuch stains may require recoating the floor or even replacing thestained tiles. This can require substantial time and expenditure. Whilesome polymers incorporated into a floor finish are synthesized using anoxidizer catalyst, the level of residual oxidizer present when thatpolymer is formulated into a floor finish composition is insufficient todecolorize stains on the coating.

While stains are eventually removable from the finish via specialtycleaners, these cleaners often do so at the expense of damage to thefloor finish, making it necessary to recoat the floor. The time andexpense of repairing the floor damage represents a substantialexpenditure on the facility's part. Therefore, a need exists for a meansof preventing or eliminating stains on floor finishes without causingdamage to the finish.

One means of avoiding stains without film damage is to incorporatecertain commercially available polymers such as Rohm & Haas's RhoplexNTS-2923 into the finish. However, these polymers are much moreexpensive than conventional polyacrylates and require highlyconcentrated specialty strippers for their removal. Additionally,polymers such as this also tend to be difficult to formulate and areoften incompatible with other polymers.

The inventors have surprisingly discovered that floor finish and/orsealer when combined with an oxidizing agent is able to decolorizestains such as coffee or mustard as they attempt to penetrate thecoating film. The end result is partial or full decolorization of thestain. This permits cleaning of any material remaining on top of thefilm with mild cleaners, or even water, to afford a clean floor coatingwithout film damage.

SUMMARY OF THE INVENTION

The present invention provides, in one aspect, a method for impartingstain resistance to a surface comprising applying to the surface ahardenable coating composition comprising an effective amount of anoxidizing agent sufficient to decolorize a stain.

In another aspect the invention provides a method for imparting to asurface resistance to oxidizable stains comprising applying to thesurface a hardenable coating composition comprising an effective amountof an oxidizing agent having an oxidizing ability sufficient todecolorize an oxidizable stain.

In yet another aspect, the invention provides a floor coated with afloor finish comprising an effective amount of an oxidizing agent havingan oxidizing potential sufficient to decolorize a stain on the floorfinish.

The oxidizing agent reacts with the stain to change the stain colorationfrom a yellowish hue (e.g., yellow-white, yellow or brown) towards alighter hue (e.g., pale yellow, white or transparent). Thisdecolorization reaction takes place over a period of minutes, hours ordays, and preferably can eventually cause the stain to disappear.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

For the following defined terms, these definitions shall be applied,unless a different definition is given in the claims or elsewhere inthis specification.

In this application, a “hardenable” coating composition is a compositionthat can be applied to a surface and then dried, cured, polymerized orotherwise converted to form a durable coating on the surface.

In this application, an “effective amount” of an oxidizing agent is anamount sufficient to at least partially decolorize a stain when appliedto a test stain and allowed to stand for one hour at room temperature. Asuitable test stain can be formed by applying prepared mustard to whitevinyl composite tiles coated with a metal-catalyzed acrylic floor finishand wiping away excess mustard. Decolorization can be evaluated byvisual observation of the stain under average overhead fluorescentillumination.

The term “substantially free” may refer to any component that thecomposition of the invention lacks or mostly lacks. When referring to“substantially free” it is intended that the component is notintentionally added to compositions of the invention. Use of the term“substantially free” of a component allows for trace amounts of thatcomponent to be included in compositions of the invention because theyare present in another component. However, it is recognized that onlytrace or de minimus amounts of a component will be allowed when thecomposition is said to be “substantially free” of that component.

The term “stain” as used herein refers to any substance that would actto discolor a permeable or semi-permeable surface such as a polymericfloor coating, cement, granite, linoleum, ceramic tile and the like.“Stain” causing substances as used herein include but are not limited tocoffee, tea, wine, cola, blood, beet juice, mustard, peach juice,chocolate, red food coloring and the like. A “stain” does not includeoxidizing agents such as iodine which would impart a dark spot on asurface but may otherwise be referred to as an oxidizer. “Stain” causingsubstances include liquids and solids.

“Blending” as used herein refers to adding or mixing a component into aprepared floor finish. That is, blending does not refer to the step ofsynthesizing a polymer for a floor finish. Said otherwise, blending doesnot refer to polymerization of the floor finish.

All numeric values are herein assumed to be modified by the term“about,” whether or not explicitly indicated. The term “about” generallyrefers to a range of numbers that one of skill in the art would considerequivalent to the recited value (i.e., having the same function orresult). In many instances, the terms “about” may include numbers thatare rounded to the nearest significant FIGURE.

As used in this specification and the appended claims, the singularforms “a”, “an”, and “the” include plural referents unless the contentclearly dictates otherwise. Thus, for example, reference to acomposition containing “a compound” includes a mixture of two or morecompounds. As used in this specification and the appended claims, theterm “or” is generally employed in its sense including “and/or” unlessthe content clearly dictates otherwise.

Weight percent, percent by weight, % by weight, and the like aresynonyms that refer to the concentration of a substance as the weight ofthat substance divided by the weight of the composition and multipliedby 100.

Unless otherwise stated, all weight percentages provided herein reflectthe active weight percent of each component. The weight percent of rawmaterial as provided by the manufacturer is easily determined from theprovided information by use of product data sheets as provided from themanufacturer.

As used herein the term, “consisting essentially of” in reference to acomposition refers to the listed ingredients and does not includeadditional ingredients that, if present, would affect the hardening orcoating ability of the floor coating composition. The term “consistingessentially of” may also refer to a component of the coatingcomposition. For instance, a solvent package may consist essentially oftwo or more solvents and such solvent package would not include anyother ingredients that would affect the effectiveness of that solventpackage—either positively or negatively. As used herein the term“consisting essentially of” in reference to a method of preparing aself-bleaching flooring refers to the listed steps and does not includeadditional steps (or ingredients if a composition is included in themethod) that, if present, would affect the method.

The invention can be used to prevent or decolorize stains caused by awide variety of products. Typical stain-causing products includefoodstuffs such as mustard, ketchup, coffee, cola, to name a few. Theinvention can be used to mask other problematic oxidizable stains thatmay be encountered, particularly those arising from the use of coloreddyes in laboratories and other food soils in cafeterias, kitchens orsupermarkets. The art and compositions of a floor finish and/or sealeris well-known to one skilled in the art. The oxidizing agentmodification of this invention should have a sufficient redox potentialas to be able to act as a chemical oxidizing agent relative to thestain. In particular, it should have a redox potential such that itwould be able to oxidize the highly colored food and beverage stains ofmustard, catsup, and red food coloring found in liquids such as Kool-Aidor Hawaiian Punch drinks Tables of redox potentials are well-known, anexample of such is found in Lange's Handbook of Chemistry, 12th edition,McGraw Hill, pages 6-2 through 6-21 which is hereby incorporated byreference for all purposes.

A variety of oxidizing agents can be employed in the invention.Preferred oxidizing agents for this invention include but are notlimited to hydrogen peroxide, hypochlorites, and organo-chlorinebleaches with hydrogen peroxide being most preferred. Preferredoxidizing agents have an electrochemical potential of less than +1.8,preferably less than +1.5, preferably less than +1.0. The inventioncontemplates that a single oxidizing agent or a combination of at leasttwo oxidizing agents could be included in a formulation of theinvention.

The oxidizing agent is included in an amount to make it effective inremoving and or preventing staining of the floor finish or sealer.Preferred levels of oxidizing agent are between about 0.5 up to about 10weight percent, from about 0.8 up to about 5 weight percent, from about0.8 to about 2 weight percent. The oxidizing agent may be incorporatedinto the finish/sealer formulation at the point of its production for aone-part product or at its point of use for a two-part product. However,it is recognized that an embodiment includes adding the oxidizing agentat the point of use to ensure that the oxidizing agent is notdeactivated during transport or storage due to incompatible pH or thegeneral instability of the oxidizing agent in combination with theuncured finish or coating.

A variety of hardenable coating compositions can be employed in theinvention. Such compositions can be made from a wide variety of filmformers. Floor finish compositions are especially preferred coatingcompositions for use in the invention. Suitable commercially availablefloor finish compositions that can be modified by addition of thereducing agent include PADLOCK™, GEMSTAR LASER™ and TAJ MAHAL™ acrylicfloor finishes from Ecolab Inc. located in St. Paul, Minn.; CORNERSTONE™and TOPLINE™ acrylic floor finishes from 3M Company located in St. Paul,Minn. HIGH NOON™ acrylic finish from Butchers; CITATION™ acrylic finishfrom Buckeye International, Inc., COMPLETE SIGNATURE™, TECHNIQUE™ andVECTRA™ acrylic floor finishes from SC Johnson Professional Products;SPLENDOR™, DECADE 90™, PRIME SHINE™ ULTRA and PREMIER™ acrylic finishesand FORTRESS™ urethane acrylic finish from Minuteman, International,Inc.; UPPER LIMITS™ acrylic finish from Spartan Chemical Co.; blends ofROSHIELD™ acrylate coating with styrene maleic anhydride polymer;COURTMASTER II™ urethane floor finish from Ecolab Inc.; strippable floorcoatings designated as “sealers” (e.g., OVER AND UNDER™ floor sealer,available from S. C. Johnson Professional Products and ACRYL-KOTE™ Sealand Finish and PREP Floor Seal from Minuteman, International, Inc.);strippable coatings based on polyvinylacetates and materials such asthose described in U.S. Pat. Nos. 4,517,330 and 5,319,018 and thepatents cited therein. The coating can also be a UV-curable coating andblends of coatings (e.g., up to 50 weight percent of a radiation curablecoating with less than 50 weight percent of a non-radiation curablecoating) can also be employed in the invention.

In an embodiment the oxidizing agent of the invention is not consumed asan initiator such as in initiating polymerization of monomericcomponents of the coating or sealant. As one may appreciate, it isdesirable that the oxidizing agent does not act to initiate anyreactions within the coating composition so that the oxidizing agentremains available to oxidize any stains that may deposit onto thecoating or sealant once it has hardened. It is known to includecatalysts to prepare polymerized compounds but that is not the inventionat hand. The coating or sealant of the invention is comprised ofcomponents that do not rely upon the catalytic potential of theoxidizing agent in order for polymerization to occur. That is, coatingcompositions of the invention are suitable as floor coatings whether ornot the oxidizing agent is added to the composition. That is, thecoating composition will perform equally as well as a hardened floorcoating or sealant whether or not the oxidizing agent is added to thecoating composition. However, adding the oxidizing agent to the coatingcomposition results in a hardened coating that is capable of reducingand/or eliminating stains placed or spilled on the hardened or curedcoating.

The skilled artisan can likely appreciate that it would becounter-productive if the oxidizing agent of the invention were consumedby a polymerizing reaction once it was added to the composition. If theoxidizing agent of the invention were consumed as an initiator orcatalyst it would not be available to act upon and removelater-deposited stains thereby rendering it useless for its intendedpurpose. If a floor coating is used for which the oxidizing agent canalso act as an initiator or catalyst of a reaction such as apolymerization, an excess of the oxidizing agent is included such thatenough oxidizing agent remains after the polymerization or otherreaction is complete to remove or bleach stains from the floor coatingonce the coating is hardened.

Component Purpose % by weight Organic Solvents Modify drying properties0.1-40   Inorganic Solvent Diluent/Carrier 10-60  Plasticizers 0.1-20  Polymer Coating surface 1-70 Resin Enhance strippability 1-20 Waxemulsion Modifies buffability and 1-20 coefficient of friction incoating

An example composition of the present invention is the following:

An exemplary composition using the present invention is the following:

Parts Parts (wt. Parts (wt. Component (wt. %) percent) percent) PurposeWater  10-60 35-50 44.8 Diluent/Carrier Diethylene glycol 0.1-20 1-5 3.0Organic Solvent monoethyl ether Dipropylene glycol 0.1-20 0.7-4.7 2.7Organic Solvent methyl ether solvent tributoxylethyl 0.1-10 0.1-3.4 1.7Plasticizer phosphate benzoate esters 0.1-10 0.1-3.0 1.0 plasticizerpolyacrylic   1-70 32-45 38.1 polymer emulsion alkali soluble resin  1-20 0.1-5.0 2.9 Additive to improve strippability polyethylene wax  1-20 2.5-9.0 5.7 Additive to emulsion modify buffability andcoefficient of friction

An oxidizing agent is added to the above-detailed composition in anamount from about 1.0 to about 10 weight percent, from about 1.5 toabout 5 weight percent, and from about 1.5 to about 3 weight percent.

Optionally, a bleach activator may be incorporated into theabove-described formulation. Nonlimiting examples of bleach activatorinclude molecules with peroxidizable functionality such as amides,esters, nitriles, carboxylates, and transition metal compounds. Thecoating composition can contain a variety of adjuvants to alter theperformance or properties of the coating composition before or afterapplication to a substrate. Useful adjuvants include inorganicparticles. Other useful adjuvants include surfactants, defoamers, waxes,indicators, colorants, optical brighteners, UV absorbers, lightstabilizers and antioxidants. The types and amounts of such adjuvantswill be apparent to those skilled in the art.

The process for preparing the floor finish/sealer without the additionof a oxidizing agent is well-known. The oxidizing agent may beincorporated into the coating composition at any stage in itsmanufacture. It may be added as a solid, powder, crystalline material,agglomerate, or solution. If necessary, solvents (glycol ethers,alcohols, water, etc.) or hydrotropes (sodium xylene sulfonate,potassium cumene sulfonate, octyldimethylamine oxide, monoethanolamine,diethanolamine, triethanolamine, ammonia and ammonium salts, etc.) maybe added to assist with solubilization of the oxidizing agent.

The compositions of the invention can be applied to a variety ofsurfaces that ordinarily suffer from staining Such surfaces includefloors (e.g., in hospitals, clinics, nursing homes, doctors' offices,dentists' offices, veterinarians' offices, grocery stores, restaurants,kitchens, and the like), non-floor architectural surfaces (e.g., walls,ceilings, countertops, cabinets and the like) and ambulance interiors.The compositions of the invention are recommended to coat and protectsurfaces whenever potentially stain-causing products are used in thevicinity.

Once prepared, the coating may be applied to the surface through avariety of means including but not limited to flat and conventionalmops, spraying, combined mechanical floor cleaning/coating,coating/burnishing equipment, or the like. Typically, the substrateshould first be cleaned and any loose debris removed. One or more coatsof the coating composition (e.g., one to five coats) are applied to thesubstrate, and allowed to dry. Each coat preferably will have a drycoating thickness of about 0.1 to about 100 micrometers, more preferablyabout 2.5 to about 20 micrometers. Preferably the overall coatingthickness will be about 5 to about 150 micrometers, more preferablyabout 5 to about 40 micrometers. It is envisioned that once dried orcured the coating surface is renewable by buffing and/or burnishing,cleaning, or applying a floor finish restorer. It is believed thatexposing an interior layer of the dried or cured coating will renew itsoxidizing ability thereby renewing both the appearance and the bleachingability of the coating.

The skilled artisan will recognize oxidizing materials are used ascatalysts in existing floor coatings to convert monomers into polymers.However, the level of oxidant catalyst is typically at very low levelsand clearly is at a level ineffective to remove or eliminate stains orthe need for the present invention would not exist. If the oxidizingagents of the present invention are added to compositions requiring aninitiator or a catalyst to polymerize the composition, the amount ofoxidizing agent, if suitable as an initiator or catalyst far exceeds theamount necessary to catalyze any polymerization reaction. That is, a deminimus amount of oxidizing agent may be consumed to catalyze apolymerization reaction; however, a substantial amount of oxidizingagent remains active to remove stains after hardening of thecomposition. At least 0.5 weight percent, at least 1 weight percent, atleast 1.5 weight percent, at least 2 weight percent, at least 3 weightpercent, at least 4 weight percent, at least 5 weight percent, and atleast 10 weight percent and at least 15 weight percent of the oxidizingagent remains in the composition after initiation of polymerization iscomplete.

The present invention incorporates or blends an oxidizing agent into afloor finish. The present invention does not include applying anoxidizing agent to a cured or hardened floor finish. This is known inthe art as cleaning a floor finish. While the present invention mayresult in a cleaned floor finish, the oxidizing agent is an integralpart of the floor finish or is blended into the floor finish before thefinish is applied to the appropriate surface.

The compositions of the present invention can be prepared by a number ofmethods. Some convenient and satisfactory methods are disclosed in thefollowing examples. The present invention can be better understood withreference to the following examples. These examples are intended to berepresentative of specific embodiments of the invention, and are notintended as limiting the scope of the invention.

EXAMPLES Example 1

This example compares the bleaching ability on a coffee stain of anoxidant-containing finish of the invention as compared to a conventionalfinish.

A conventional floor finish commercially available from Ecolab asGemstar Laser™, was compared with a variation of its formula containing2 weight percent hydrogen peroxide. Gemstar Laser™ is a polyacrylatefinish that is manufactured by using an oxidizer-initiated polymer. Avinyl composite floor tile was divided in half. One half of the tilefloor was coated 4 times with Gemstar Laser™ finish (Control). The otherhalf of the tile floor was coated 4 times with Gemstar Laser™ finishmodified with 2 weight % hydrogen peroxide (invention composition). Oncedry, each half of the finish-coated tile was treated with a solution ofcoffee/creamer/sugar which was allowed to dry on the tile overnight. Thenext day it was noted that the coffee stain on the invention portion(floor finish with 2 weight percent hydrogen peroxide) of the tileturned from dark brown to colorless. The entire tile was then rinsedwith tap water. The invention treated section was free of color whilethe control section retained a light yellow tint. The Controldemonstrates that the oxidizer used to initiate the polymerization ofthe polyacrylate in the floor finish is consumed by the initiationreaction and enough residual oxidizing agent is not present todecolorize or to oxidize the coffee stain. No film damage was noted forthe invention treated section after rinsing.

This Example demonstrates that compositions of the invention areeffective at preventing stains (as compared to conventional finishcompositions) without any apparent film damage.

Example 2

In this Example, a composition of the invention was applied to anexisting floor finish as a top coat.

A conventional floor finish commercially available from Ecolab asGemstar Laser™, was compared with a variation on its formula containing2 weight percent hydrogen peroxide. A vinyl composite floor tile wascoated 3 times with Gemstar Laser™ coating. The tile was then dividedinto halves. One half was coated with Gemstar Laser™ (Control) and theother half coated with Gemstar Laser™ modified with peroxide per theinvention. The resulting tile was treated overnight on each half with asolution of coffee/creamer/sugar. The next morning the tile was observedand it was noted that the stain on the invention-coated portion of thetile turned from dark brown to colorless. The entire tile was thenrinsed with tap water. The invention-coated section was free of colorwhile the control section had turned a light yellow color. This Exampledemonstrates that compositions of the invention are effective atpreventing stains even when used to coat over conventional finishcompositions.

Example 3

This Example demonstrates that compositions of the invention aresuitable for eliminating red wine stains.

White vinyl coving was coated with either Laser™ floor finish or Laser™floor finish containing 1 weight percent hydrogen peroxide per theinvention. After drying, the tiles were treated with an aliquot of redwine that was allowed to dry in place. Within 1 hour, the inventionfinish had bleached the stain away while the unmodified control finishshowed a distinct wine stain remaining.

Example 4

This Example demonstrates that organo-chlorine bleach is an effectiveoxidizing agent in compositions of the invention.

Laser™ floor finish was modified with 1 weight percenttrichloro-s-triazinetrione as a source of chlorine bleach. The finishwas applied to a floor tile and, after drying, several staining agents(mustard, coffee, red wine, grape juice, ketchup, mustard) were appliedand allowed to dry. The dried stains were then lightly wiped with a wettowel leaving residual stains in place. Within 15 minutes, all stainsexcept the mustard and wine were fully decolorized. Within two days,only a very slight residual stain of wine remained.

Example 5

This Example demonstrates that sodium hypochlorite is an effectiveoxidizing agent in compositions of the invention.

Laser™ floor finish was modified with 1 weight percent sodiumhypochlorite bleach as a source of chlorine bleach. The finish wasapplied to a floor tile and, after drying, several staining agents(mustard, coffee, red wine, grape juice, ketchup, mustard) were appliedand allowed to dry. The dried stains were then lightly wiped with a wettowel leaving residual stains in place. Within 15 minutes, all stainsexcept the mustard and wine were fully decolorized. Within two days,only a very slight residual stain of wine remained.

Comparative Example

The invention has been described with reference to various specific andpreferred embodiments and techniques. However, it should be understoodthat many variations and modifications may be made while remainingwithin the spirit and scope of the invention. Modifications ofproportions, the elements, materials, and components used in thepractice of the invention, and otherwise, which are particularly adaptedto specific environments and operative requirements are envisioned bythis application without departing from those principles. The appendedclaims are intended to cover and embrace any and all such modifications.

We claim:
 1. A coating composition comprising an anionic hardenablefilm-former chosen from acrylate, urethane, acrylate with styrenecopolymer, or combinations thereof, polyethylene wax, and at least 0.5weight percent of an oxidizing agent sufficient to decolorize a stain onthe film-former, wherein the oxidizing agent comprises hydrogenperoxide, hypochlorite, organic peroxides, organo-chlorine bleaches or acombination thereof and wherein the oxidizing agent is not consumed byinitiating or catalyzing a reaction in the film-former composition, thehardened film-former decolorizes stains when contacted with stainingsolution for at least up to 48 hours, and wherein the composition issubstantially free of surfactants.
 2. A composition according to claim 1wherein the oxidizing agent comprises hydrogen peroxide.
 3. Acomposition according to claim 1 comprising about 0.8 to about 5 weightpercent oxidizing agent.
 4. A composition according to claim 1comprising about 0.8 to about 2 weight percent oxidizing agent.
 5. Acoating composition according to claim 1 wherein the film-former forms ahardened film resistant to rinsing with tap water.
 6. A hardenablecoating composition, comprising an anionic polymer chosen from acrylate,urethane, acrylate with styrene copolymer, or combinations thereof,solvent, plasticizer, and at least 0.8 wt percent oxidizing agentwherein the oxidizing agent is not consumed by initiating or catalyzinga reaction in the hardenable coating composition, and the hardenedcoating composition decolorizes stains when contacted with stainingsolution for at least up to 48 hours.
 7. The coating compositionaccording to claim 6 wherein the polymer is comprised of polyacrylate oracrylate copolymer.
 8. The coating composition according to claim 6wherein the plasticizer is comprised of benzoate esters.
 9. The coatingcomposition according to claim 6 wherein the solvent is comprised ofdiethylene glycol monoethyl ether and dipropylene glycol methyl ethersolvent.
 10. The coating composition according to claim 6 furthercomprising water.
 11. The coating composition according to claim 6wherein the oxidizing agent is comprised of hydrogen peroxide.